Electrical winding for a transformer, a choke coil or the like

ABSTRACT

The invention relates to an electrical winding for a transformer, a choke coil or the like, particularly for high frequencies, wherein the conductor forming the winding is radially subdivided into n subconductors and within the winding the subconductors are twisted in such a manner that the initially innermost subconductor, after twisting comes to lie outermost, the subconductor in the second innermost position, after twisting comes to lie at the second outermost position, etc. If the subconductors are designed as conductor tapes, the subconductors 1 through (n-1) comprise two partially overlapping tape sections which in the overlap region are conductively connected together at the side edges of the tape, the n th  conductor tape being made of one piece and forming one of the outwardly disposed subconductors of the conductor. 
     The conductor tapes 2 through n are laced through between the overlapping tape sections of the first subconductor, the conductor tapes 3 through n are laced through between the overlapping tape sections of the second subconductor, the n th  tape being laced through between the overlapping tape sections of the (n-1) th  conductor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an electrical winding for a transformer, achoke coil or the like wherein the conductor forming the winding issubdivided in the radial direction into n subconductors and, within thewinding, the subconductors are twisted in such a manner that theinitially innermost subconductor, after twisting, becomes the outermostsubconductor, the second most inwardly disposed subconductor, aftertwisting, becomes the second most outwardly disposed subconductor, etc.

2. Description of the Prior Art

It is known from German Pat. No. 902,042 and from Richter, "ElectricalMachines III", published by Birkhauser Verlag, 1963, pages 208-209, tosubdivide in the radial direction the conductor forming the winding andin the course of the winding twist the subconductors in such a mannerthat the initially outermost subconductor, after twisting, comes to lieinnermost, the subconductor initially lying in the second most outwardposition, after twisting, comes to lie at the second most inwardposition, etc. In both cases, the reason for doing this is stated to bea reduction of eddy current losses.

It is the object of the invention to provide a tape winding in which aplurality of superposed tapes, whose ends are connected electrically inparallel, form the conductor with such twisting that the windingoperates essentially without losses.

SUMMARY OF THE INVENTION

This problem is solved in that during forming of the subconductors intoconductor tapes, the subconductors 1 through (n-1) include two partiallyoverlapping tape sections which are conductively connected together attheir lateral edges in the overlap region, that the n^(th) conductortape is made of one piece and forms one of the outwardly disposedsubconductors of the conductor, that the conductor tapes 2 through n arelaced through between the overlapping tape sections of the firstsubconductor, that the conductor tapes 3 through n are laced throughbetween the overlapping tape sections of the second subconductor, etc.until finally, the n^(th) tape is laced through between the overlappingtape sections of the (n-1)^(th) conductor.

In order to avoid excess "bulk" in the winding at one point, the regionsof overlap are preferably offset somewhat with respect to one another inthe direction of winding.

Favorably, the region of overlap is selected of such a width that theconductive connection between the overlapping tape sections correspondsapproximately to the width of the conductor and thus there will be nosignificant increase in ohmic resistance due to the configuration of thetapes.

The basic idea of the conductor design can be realized in practice invarious ways. In one possible way, two tape sections are permitted tooverlap during the production of the first through (n-1)^(th) conductortapes and these two tape sections are connected along one lateral edgeof the tape in the overlap region.

According to another possible solution, the first through (n-1)^(th)conductor tape are initially folded about an edge which is inclined by45° with respect to the winding direction; then the folded portion isfolded again in a further fold about an edge inclined by 45° withrespect to the direction of winding so that the folded conductor tapeagain extends in the winding direction, but is offset by about one tapewidth, finally, by folding the offset portion about the lateral edge ofthe tape in the overlap region back into the path of the winding, thedesired tape configuration is realized.

According to a third possibility, the first through (n-1)^(th) conductortapes are each produced in that in a tape of double width two regionsare produced, by cutting away or the like of one-half a tape width, withthe conductor tapes offset with respect to each other by one tape width.These two regions must in part overlap and then the one tape region isfolded by 180° in the direction of winding about the edge connecting thetwo regions.

In all three cases, a continuous conductor tape is produced which,however, in the overlap region permits other tapes to change from oneside of the tape to the other. The latter method has the advantage thatit can be produced by folding and does not add much bulk, particularly,if the overlap regions are additionally offset with respect to oneanother. However, this method requires a relatively large amount ofcopper.

According to a further feature of the invention, the point of twistingof the individual subconductors is placed at least in the vicinity ofthe point on the length of the winding where the fluxes through thesurface areas of the partial loops are identical. With such anarrangement of the point of twisting, it is accomplished that thecurrents generated by axial flux in the individual loops make no or onlya small contribution to the losses. Thus, this measure is of particularinterest, for example, for transformers having a high degree ofefficiency. This dimensioning is not limited to tape windings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be explained with the aid of thedrawings, wherein:

FIG. 1 shows a twisted conductor including four subconductors;

FIG. 2 is a basic diagram of the path of the tape sections of thepresent invention showing a top view onto the lateral edges of the tape;

FIG. 3 illustrates an embodiment showing the configuration of theindividual tapes;

FIG. 4 depicts a second embodiment showing the configuration of theindividual tapes;

FIG. 5 is a basic sketch for determining the position of the point oftwisting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows, in its unwound state, the conductor of an electricalwinding of length l composed of four mutually insulated conductors 1-4.The subconductors are short-circuited at their ends 5 and 6. Thesubconductors 1-4 are twisted in such a manner that the subconductor 1initially lies at the uppermost position and later at the lowermostposition, conductor 2 initially lies at the second position from thetop, later at the second position from the bottom, etc. This reduceslosses.

If the winding is designed as a tape winding, the subconductors 1-3 mustpermit the changeover of other subconductors from one side of the tapeto the other while the subconductor 4 is designed as a continuous tape.This is shown in principle in FIG. 2 which shows the four subconductors1-4 in a top view seen toward the side edges. However, in order toillustrate the invention, it was necessary to distort the axisperpendicular to the conductor. It can be seen that the subconductor 1(solid line) is initially at the top, later at the bottom. Thesubconductor has an overlap region 7 in which the two separatelyillustrated parts of the subconductor 1 are connected together at theirlower edges. This connection is shown by hatching, however in thedistorted illustration. The connection is formed by the edge and not--as shown--by an area. In reality, the parts of the subconductor 1 lieon top of one another in the overlap region unless other subconductorsare laced through. Between the two parts of the subconductor 1, theother three conductors 2-4 change toward the other side of the tape. Thewidth of the connection of the two conductor parts, i.e. of the overlapregion, corresponds to the width of the tapes.

The subconductors 2 and 3 (shown in dash-dot or dashed line,respectively) are constructed in the same manner. Through them,conductors 3 and 4 or only 4, respectively, change over to the otherside of the tape. The overlap regions 7-9 are somewhat offset withrespect to one another. The conductor 4 (shown by a dotted line) is acontinuous tape. In the overlap region, the subconductors 1-3, accordingto the embodiment of FIG. 3, are produced in such a manner thatinitially the subconductor 10 is folded about an edge 11 (FIG. 3a), thenthe folded portion 10a is again folded about an edge 12 inclined by 45°so that the folded portion 10a is offset by about the width b withrespect to part 10 and finally part 10a is folded back about edge 13 toproduce the desired subconductor. The overlap region is here identifiedwith the numeral 14.

According to FIG. 4, a conductor having two regions offset by b and theoverlap region 22 is formed of a conductor tape of the width 2b bysevering the parts 20 and 21 (FIG. 4a). Folding about the edge 23 thenproduces the conductor (FIG. 4b).

The same configuration as in FIG. 4b will also result for the conductorif two separate tape sections are placed on top of one another in theoverlap region and are conductively connected at edge 23.

For a conductor formed of two subconductors 30 and 31, FIG. 5a shows byway of circles 33 the distribution of the magnetic flux penetrating theloop. The resulting current which causes considerable losses isindicated by arrows 32.

If the twist is placed so that the total flux through loop sections 34and 35 is identical, the currents generated in the loop sections 34 and35 are compensated and losses are avoided. This teaching can also beemployed in an arrangement having four conductors as shown in FIG. 2,but then the overlap regions 7-9 must be placed in the vicinity of therespective point on the length of the conductor. This is shown in FIG. 2by the asymmetrical position of the overlap regions on the length of theconductor. The exact position of the point depends on the leakage fluxcurve in the given magnetic circuit, which may be different from case tocase. Normally, it can be assumed, however, that the leakage flux ofinterest decreases practically linearly from the surface of the windingtoward the magnetic yoke to there become equal to zero. With thisprerequisite, the point of twisting lies at about 30% of the conductorlength l, measured from the end of the winding disposed in the area ofintensive leakage flux.

I claim:
 1. An electrical winding having a conductor which is radiallysubdivided into 1 through n subconductor tapes, and wherein within thewinding said subconductor tapes are twisted in such a manner that thetape initially lying innermost, after twisting, comes to lie outermost,the tape lying at the second innermost position, after twisting, comesto lie at the second outermost position, etc., wherein the improvementcomprises that the subconductor tapes 1 through (n-1) are formed of twopartially overlapping tape sections which in the overlap region areconductively connected together at the side edges of the tape sections;that the n^(th) subconductor tape is made of one piece and forms one ofthe outwardly disposed subconductor tapes of the conductor; that thesubconductor tapes 2 through n are laced through between the overlappingtape sections of the first subconductor tape; that the conductor tapes 3through n are laced through between the overlapping tape sections of thesecond subconductor, the n^(th) tape being laced through the overlappingtape sections of the (n-1)^(th) conductor, each of the first through(n-1)^(th) conductor tapes being produced from a double width tapewherein two regions are formed by severing half the tape width, theconductor tape extending in said region being offset with respect toitself by one tape width and said regions overlapping in part, one taperegion being folded about the side edge of the tape by 180° in theoverlap region.
 2. An electrical winding according to claim 1, whereinthe overlap regions of the subconductor tapes are somewhat offset withrespect to one another in the direction of winding.
 3. An electricalwinding according to claim 1, wherein the width of the conductiveconnection between overlapping tape sections corresponds approximatelyto the width of the tape.
 4. An electrical winding according to claim 1,wherein the points of twisting, particularly the overlap regions of theindividual subconductors, lie at least in the vicinity of the point onthe length of the winding at which the fluxes in the loop areas of thethus formed loops are identical.